Project Summary Osteoarthritis (OA) is prevalent among veterans, causes substantial disability, and is associated with a huge economic burden. Although problematic symptoms are a primary reason that people seek medical care, the treatment provided is largely pharmacological, despite recommendations that behavioral strategies to manage symptoms are an important part of OA treatment. The study team has demonstrated in a previous pilot study that a brief activity pacing intervention specifically tailored to individuals' recently-experienced symptoms and physical activity patterns and provided by healthcare professionals had large effects on fatigue severity and fatigue interference in daily activities. The overall objective of this study is to examine the effectiveness of a tailored activity pacing intervention on pain, fatigue, and physical function using a randomized controlled trial design with a 6 month follow-up period. The main hypothesis is that tailored activity pacing will be most effective at reducing symptom severity and improving physical function. Veterans and non-veterans between the ages of 50-80 years (N = 156) who present with both radiographic evidence of knee or hip OA and moderate to severe pain will be randomly stratified by age and gender into one of three treatment arms: tailored activity pacing, general activity pacing, or usual care. The tailored and general activity pacing interventions involve three clinic visits and two home monitoring periods in which participants wear an enhanced wrist-worn accelerometer that measures continuous physical activity and allows for input of symptom severity. Both the tailored and general interventions address activity pacing in individual sessions with an occupational therapist, but only the tailored intervention involves education based on individuals' symptoms and activity patterns from the home monitoring periods. Outcome measures for all participants will be collected at baseline, 10 weeks, and 6 months post baseline. Repeated measures analysis of variance models will be used to analyze the effect of treatment on the primary outcomes. The proposed study will provide a rigorous test of effectiveness of activity pacing, a recommended approach for OA that has not been tested as a stand-alone modality other than in the previously mentioned pilot work. Because OA symptoms are chronic, fluctuating, and interfere with daily activities, a focused, individually-tailored approach to symptom management may provide lasting benefit and enhance currently available non-pharmacological treatment options for OA.